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Rubber tire molds

Maintaining Molds for Rubber Molding, Protecting Your Investment

Molds utilized in rubber molding processes, including the manufacture of pneumatic tires, often represent a significant investment. In addition, the mold is a key factor in determining the end quality of the parts being produced, the efficiency of the process, the rate of scrap and the downtime in the process. Given all of these issues, it is wise to keep the molds clean and well protected to maximize their useful life and keep them producing parts efficiently. Based on our experience of working with a wide range of molding operations, Chem-Trend understands the importance of molds and we have developed a wide variety of products to help protect this important component in the molding process.

There are several occasions when the mold can be best cared for, such as when a mold is being built or when a mold has been taken out of production and disassembled for thorough cleaning and/or repair. The advantages to applying the mold release system when the mold is fully disassembled are:

  • All parts and surfaces of the mold can be thoroughly cleaned. All blasting media, if used, can be blown from corners and crevices.
  • The mold is not contaminated with any other mold release system.
  • The mold surface will have been machined or polished to the point where it would be expected to produce perfect moldings.
  • All parts of the mold and mold surfaces are easily accessible.
  • Mold parts can be treated in an area of the facility that allows solvent-based products to be used (if desired). Mold surfaces would be at room temperature where solvent-based products evaporate off faster than water-based products.

Once back in the molding press, the prepared mold should be heated to the molding temperature and given a final coat of the chosen mold release agent before molding begins.

Very often, the first-off moldings from a new or just-cleaned mold would be thrown away as a reject part. In the case of a new mold, this can be accepted because the rubber charge weight or the molding parameters may not be quite known, for instance. Most often, though, parts are thrown away because of poor appearance or molded-in defects, brought about by contaminants that have been left on the surface of the mold. It is entirely possible to ensure that the mold surfaces are “ready for action” by preparing them with a semi-permanent mold release.

In the case of a just-cleaned mold, all molding parameters are known, meaning that the start-up process can be faultless – provided the semi-permanent system is applied carefully and correctly. Excellent parts can be made from “shot one”.

If a mold is to be stored for an extended period of time, especially if stored in a moist environment, then a custom-designed mold protector should be applied to all surfaces prior to storage.

Mold Protectors for Rubber Molding Operations

Chem-Trend understands the importance of maintaining molds in good working condition and has developed a line of high quality mold protectants to work in conjunction with our line of semi-permanent release agents for the rubber industry.

Mold protectors can be the dry polymeric film type that provides good short-term mold corrosion protection, with the added benefit of assisting in mold start-up. Or, mold protectors can be the more mobile varieties that are designed with the long-term storage of molds in mind.

  • Our mold protectant products offer:
  • Excellent rust protection for just-cleaned molds
  • Short-term or long-term storage protection options
  • Short-term protection while providing excellent mold start-up
  • Compatibility with either semi-permanent or conventional release agents
  • Long-term storage protection to shut out rust completely
  • Complete mobility for protecting even the tiniest mold detail
  • Easy removal during mold start-up procedures

Our experience in the rubber molding industry spans more than three decades. Please contact us and let us show you how we can help you address the challenges of protecting your molds and increasing their efficiency.

Anti-Corrosion Coatings for Tire Molds

Avoiding corrosion of expensive tire molds, especially on steel sidewall plates, after cleaning and during storage, is an important part of maintaining the mold in good condition and prolonging its life. Often mineral oils or greases are applied to molds placed in storage for a period of more than one week. These materials function as very effective rust inhibitors, but it requires a lot of work to remove them from the surface prior to the mold being placed back into service. It is also not unusual to have to downgrade or scrap the first tire molded in a mold that has been protected with mineral oil based products because of poor cosmetic appearance.

Chem-Trend mold conditioners and treatments eliminate the need to clean a treated mold prior to reinstallation into a curing press. These products are specifically designed for application to the cool surfaces of molds that have been removed from the curing press for maintenance and/or cleaning. A solvent-based material is necessary in these unique circumstances to ensure good wetting of the cool surface and to avoid flash corrosion of the freshly cleaned metal surface. Once applied, typically with the use of hand-held spray guns, the solvent quickly evaporates leaving a coating across the surface of the mold that seals it against corrosion. The film also offers protection against corrosion to molds that are stored for prolonged periods, up to one year. Solvent-based mold treatments from Chem-Trend do not require cleaning from treated molds prior to being placed back into service, thus maximizing efficiency.

To learn more about the products that Chem-Trend has to aid in the manufacture of tires click here.